This invention relates to an apparatus and method for testing packages. More particularly, the invention relates to an apparatus and method used for pressure testing the integrity of packages containing fluid materials.
Increasingly, viscous materials and other fluids, such as liquids, pastes, creams, and grease (hereinafter fluid materials), are sealed within containers or packages made of flexible or semi-ridged materials. The packages, usually constructed from plastic sheeting or blanks of laminated paper stock, are formed in a machine which folds the blanks or sheeting to align the marginal edges of the package side walls. To seal the fluid material within the package, the marginal edges of the partially formed package are typically heat welded or adhesively secured together forming a seam.
The material forming the package is sufficiently strong so as to withstand the external forces that normally will be applied to the package during shipping and consumer usage. The packages are unsuitable for use if they allow the fluid material to leak. Bad packages are to be expected during production. although some bad packages have gross defects, others may appear acceptable but have small sealing defects which will leak if pressure is applied to the package over a period of time.
In order to provide package sealing quality assurance, it is desirable to periodically test samples of packages for compliance with sealing standards. It has proven extremely inefficient and costly to test samples or packages one at a time. This is readily apparent when one considers that a testing cycle can take five minutes or longer per package.
With the above in mind, it is a object of this invention to provide an apparatus and method in which a number of packages can be simultaneously tested over a period of time, thereby more efficiently promoting production and testing. Additionally, the invention permits the testing procedure to be halted with respect to an individual package, upon detecting failure of that individual package. The failed package can be readily removed from the machine of this invention and inspected while the test cycle for other packages continues.
An additional object of this invention is to provide for a testing apparatus and method which is dependable and economical in construction, maintenance, and operation.
In achieving these and other objects, the present invention provides for an apparatus in which a multiple number of fluid filled packages can be simultaneously tested. The apparatus includes a number of testing stations, each having an actuator for driving a movable ram. The ram presses a platen against the package being tested for a preselected time period and with a predetermined amount of force. If a package develops a leak and fails, the platen and ram will collapse on the failed package under the force of the actuator. A sensor, monitoring for failure monitoring displacement of the ram, will indicate that failure of the particular package has occurred. Once failure has been detected, a controller will cause the actuator of that specific testing station to retract the ram and platen. This allows for the failed package to be removed and inspected while the testing procedure with respect to the remaining packages, continues.
In setting up the testing sequence, a test operator inputs the length of the test period, the desired test force or pressure and any additional information into a controller which will automatically control advancement and retraction of the rams by their respective actuators. The controller is also coupled to the failure sensors and, upon an indication that failure has occurred, will cause the corresponding actuator to retract. If desired, the controller can be setup to provide a hard copy output of the test data for each test station including, for example, overall test duration, time of failure, and package lot number.
As can be seen from the above discussion, an important feature of the testing method and apparatus is that the failed packages can be evaluated without interruption of the testing cycle with respect to the remaining packages. Thus, package evaluation and production proceeds in an efficient manner.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.